I find it hard to believe I am writing this, but I forgot to mention my return trip from Santorini (then ATH-JFK-BOS). I never say anything good about JFK, so this is worth noting. The immigration control has been changed to primarily (if not solely -- our flight attendants gave conflicting accounts before arrival) electronic. If you arrive with dozens of other international flights this will only help minimally, but my flight landed early, and it turned out the flight attendant who said US citizens could ONLY use the electronic version were correct. You go in, scan your passport (like at airport kiosks when checking in) and fill out certain stuff, get a receipt, then go straight to either baggage pickup (I never have any) and straight to passport control. That line was very long because there initially was only one agent on duty, but a second soon arrived and it went more swiftly than anything else that happens at JFK.
So, finally, I have something good to say about JFK. Does anyone know if this is being done at other US airports that serve international destinations?